Alone,
mild cognitive impairment quadruples a teen’s risk of early dementia,
and poor fitness contributes to a 2.5 times greater risk, the Swedish
research team found.

Though dementia encompasses many diseases,
Alzheimer’s is the most common form. About 4 percent of the 5 million
Americans with the disease are classified as early-onset, meaning that
their symptoms begin as early as their 30s or 40s, according to the Alzheimer's Association.

How Intelligence and Exercise Affect the Young Brain

Researchers
at the Sahlgrenska Academy at the University of Gothenburg examined
data from more than 1.1 million men involved in a national cohort study.
Beginning at age 18, the men underwent regular exams for 37 years,
providing objective data on their fitness levels and intelligence.

After adjusting for outlying factors such as heredity,
medical history, and social-economic status, researchers found a
connection between age, intelligence, and early-onset dementia.

Previous
research makes experts confident that poor cardiovascular health in old
age can contribute to the development of dementia.

“Now, for the
first time, we can show that the increased risk also applies to
early-onset dementia and its precursors,” said lead researcher Jenny
Nyberg in a statement.

Early-onset dementia can be particularly hard on people who are working age, often with families to support.

“This
makes it important to initiate more research into how physical and
mental exercise can affect the prevalence of different types of
dementia. Perhaps exercise can be used as both a prophylactic and a
treatment for those in the risk zone for early-onset dementia,” Nyberg
said.

A Lifetime of Regular Exercise Is the Best Prevention

While
the cause of early-onset dementia has largely eluded experts, the new
study adds to the growing body of evidence that links cardiovascular
health to protecting the brain.

“We already knew that
physical and cognitive exercise reduces the risk of neurological
disease. Physical exercise increases nerve cell complexity and function
and even generation of new nerve cells in the adult brain, which
strengthens our mental and physiological functions,” said senior author Georg Kuhn,
a neuroscientist at the University of Gothenburg. “In other words, good
cardiovascular fitness makes the brain more resistant to damage and
disease.”

Last fall, a study published in the journal Cell Metabolism identified
a specific protein released during exercise that promotes brain health.
Harvard Medical School researchers say it could be used to develop
drugs to guard against neurodegenerative diseases and protect brain
function in seniors.

Until those drugs are available, getting
regular exercise and challenging your brain are the best ways to stave
off mental decline. Eating a diet low in fat and cholesterol has also
been shown to reduce a person’s risk of arterial stiffness, which has
also been linked to an increased risk of dementia.

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